All older adults experience some degree of cognitive compromise as they age and approximately 32% of adults aged 85 and older suffer from Alzheimer's disease. The Alzheimer's Association estimates that delaying the onset of AD symptoms by only five years would reduce the rate of incidence by 50 percent! The present Phase III clinical trial builds on a wealth of observational work and more recent experimental research conducted in the PI's lab, which suggest that an important element of maintaining cognitive vitality for life is sustained engagement in mentally-challenging activities. In a U.S. sample of cognitively normal adults, we recently demonstrated that older adults who were randomly assigned to learn digital photography, quilting, or both, in fast-paced, demanding classes for 15 hours per week for three months, showed enhanced episodic memory function?both at the end of the engagement period and, importantly, one-year later. The observed memory improvements were in comparison to two active control conditions that were low in new learning: a social engagement group that had fun but did not engage in active learning, and a placebo condition where participants worked on low-effort cognitive tasks that relied on use of previous knowledge. We also found similar facilitation effects when older adults were trained to use many different applications on an iPad. We most recently reported that older participants who participated in high-effort engagement conditions showed an increase in neural efficiency, exhibiting a change in neural activity from a pre-intervention pattern characteristic of older adults to a post-intervention pattern typical of young adults. Based on these findings, which included relatively small numbers of subjects, we propose a definitive Phase III trial to determine whether mentally challenging activities facilitate memory in cognitively normal adults via changes of neural structure and function. To isolate the critical role of mental effort, we include moderate challenge conditions and we also measure the impact of the intervention on engagement in everyday life for a full year. Finally, to maximize the scientific yield from the proposed trial, it will be conducted at two culturally diverse sites (Germany and the United States) providing an exceptionally strong test of the generalizability and reliability of positive findings. The proposed project address a critical public health issue as little is known about what steps individuals can take to maintain a healthy mind. Ultimately, we expect that sustained engagement in new learning could delay both normal age-related cognitive decline and potentially even slow the onset of AD- related cognitive symptoms.